Wikipedia:Today's featured article/June 30, 2008

Oxidative phosphorylation is a metabolic pathway that uses energy released by the oxidation of nutrients to produce adenosine triphosphate (ATP). Although the many forms of life on Earth use a range of different nutrients, almost all carry out oxidative phosphorylation to produce ATP, the molecule that supplies energy to metabolism. This pathway is probably so pervasive because it is a highly efficient way of releasing energy, compared to alternative fermentation processes such as glycolysis. During oxidative phosphorylation, electrons are transferred from electron donors to electron acceptors such as oxygen, in redox reactions. These redox reactions release energy, which is used to form ATP. In eukaryotes, these reactions are carried out by a series of protein complexes within mitochondria, whereas in prokaryotes, these proteins are in the cells' inner membranes. These linked sets of enzymes are called electron transport chains. Although oxidative phosphorylation is a vital part of metabolism, it produces reactive oxygen species such as superoxide, hydrogen peroxide and free radicals, damaging cells and contributing to aging and disease. The enzymes carrying out this metabolic pathway are also the target of many drugs and poisons that inhibit their activities. (more...)